In such a rotary tablet press, the turret is positioned in the compression section in a position of use of the rotary tablet press, i.e. when the tablet press is in working operation. The turret comprises a number of parts or components including a die disc secured between a top punch guide and a bottom punch guide. Alternatively, the die disc is integral with the top and/or bottom punch guide in a one-part or two-parts turret. The turret is driven in rotation by means of a spindle coupled to driving means and the entire turret thus rotates during operation. A powder or granular material is fed into the die bores of the rotary tablet press by means of a feeder connected to the press housing. The rotation entails, i.a., that the punches accommodated in the top and bottom punch guides are reciprocated to compress the material to tablets.
In order to carry out a change-over in the production, e.g. from one material to another or from one tablet size or shape to another, or from one press station to multiple press stations, or change-over from single layer to multilayer (such as bilayer or several layers) production, and/or to and from dry-coated tablet production, the entire turret and auxiliary components are traditionally removed in order to clean the turret or to replace the punches and dies in the turret or to install or remove various components (e.g. switch from single layer to double layer). Subsequently, the turret and auxiliary components are positioned back into the compression section and possibly adjusted.
However this arrangement has a number of drawbacks. First, various auxiliary components need to be removed from press, before turret can be removed, which in turn affects the change-over time. Second, auxiliary components can also only be installed if the turret is positioned back in the press housing.
In order to solve this, solutions have been suggested to remove auxiliary components together with turret. Examples of prior art tablet presses are described in EP 1 050 399 A2, and in WO 03/020499 A1 resulting in EP 1 423 260 B1 to Courtoy and the commercially available tablet press MODUL™ making use of the Exchangeable Compression Module (ECM) concept. However, when the turret is shifted from one press to another, re-adjustment might therefore be needed, again increasing change-over time. Even in the suggested solution, the auxiliary components are however referenced to press housing, in particular the frame thereof, and the position of the components can only be adjusted when the turret is installed inside the press.
Adjustment of components inside press is not easy due to limited accessibility in the press, especially in case of multilayer configuration with several components present in the turret and the housing as such, and also in the case of dry-coated tablets where an intake system is needed to place the cores inside the die bores. This is also the case in prior art apparatus in which the possibility of keeping the compression zone contained and washing the ECM off line is provided, in order to ensure that no cleaning of press housing is needed, hence facilitating fast change-over. However, accessibility and cleanability are not necessarily made more easy, especially when several components are present such as in multilayer production.
However, in all of the above prior art tablet presses, although providing well-functioning solutions, it is a challenge to ensure that all parts of the rotary tablet press are positioned accurately in order to secure proper functioning.